> > I'll dig into this. This sounds a way more reasonable approach.
> 
> Thanks.  Another thing that may help, if it turns out that we do
> want to let agent run when it wants to

I did some digging on the reason as to why this was happening. It turns
out there is a bug on gnupg. As of gpg 2.1.21, all operations require an
agent running (BTW --no-use-agent is effectively a no-op now). 


Given that on versions 2.19-21, they changed the way sockets are
created to be stored on /run/user/UID/gnupg/... deleting the $GNUPG_HOME
directory wouldn't flush the agent socket, and would leave an agent
instance per test running, possibly forever. E.g., make test would
result in the following:

    santiago at ~ ✔ pgrep -a gpg-agent
    632 gpg-agent --homedir /git/t/trash directory.t6050-replace/gpghome --use-standard-socket --daemon
    1192 /usr/bin/gpg-agent --supervised
    2939 gpg-agent --homedir /git/t/trash directory.t5801-remote-helpers/gpghome --use-standard-socket --daemon
    4656 gpg-agent --homedir /git/t/trash directory.t6300-for-each-ref/gpghome --use-standard-socket --daemon
    5427 gpg-agent --homedir /git/t/trash directory.t7510-signed-commit/gpghome --use-standard-socket --daemon
    5898 gpg-agent --homedir /git/t/trash directory.t6302-for-each-ref-filter/gpghome --use-standard-socket --daemon
    7747 gpg-agent --homedir /git/t/trash directory.t7003-filter-branch/gpghome --use-standard-socket --daemon
    12922 gpg-agent --homedir /git/t/trash directory.t7600-merge/gpghome --use-standard-socket --daemon
    13572 gpg-agent --homedir /git/t/trash directory.t7004-tag/gpghome --use-standard-socket --daemon
    14521 gpg-agent --homedir /git/t/trash directory.t5534-push-signed/gpghome --use-standard-socket --daemon
    16563 gpg-agent --homedir /git/t/trash directory.t5541-http-push-smart/gpghome --use-standard-socket --daemon
    17853 gpg-agent --homedir /git/t/trash directory.t7030-verify-tag/gpghome --use-standard-socket --daemon
    29858 gpg-agent --homedir /git/t/trash directory.t7612-merge-verify-signatures/gpghome --use-standard-socket --daemon
    31100 gpg-agent --homedir /git/t/trash directory.t4202-log/gpghome --use-standard-socket --daemon

Other projects such as notmuch opted for a solution that's simlar to
what I had suggested[1], but I wonder if it's even necessary to do.
There is already a fix on the master branch of gnupg[2], which I imagine
will show up to the next version of gpg2.

I don't think it would make sense to fix anything on our side, unless we
want to be extra sure the test suite is not leaking agents for all gpg
versions (including these minor versions). 

What is your take?

Thanks!
-Santiago.

[1] https://paste.debian.net/976970/
[2] https://dev.gnupg.org/T3218